1. Field of the Invention
The present invention relates to a camera apparatus such as a surveillance camera and a method of controlling the camera apparatus which uses a filter such as a polarization filter and is required to obtain an optimum image in a short time.
2. Description of the Related Art
There has been used a camera apparatus which obtains external information by processing an image imaged using a polarization filter (see JP-A-9-266572, for example).
The camera apparatus disclosed in JP-A-9-266572 is mounted on a vehicle and used to obtain external information by imaging a subject outside of the vehicle.
As shown in FIG. 8, a camera apparatus 100 is a CCD (Charge Coupled Device) camera and provided with a CCD 101 as an image pickup device. An objective lens system 102, as an imaging optical system for imaging a subject image on the imaging area of the CCD 101, is disposed on the front side of the CCD 101.
On the front surface side of the objective lens system 102, a polarization filter 103, which transmits only a light beam of predetermined polarization component to thereby eliminate an unnecessary light beam, is provided within an optical path. The polarization filter 103 can be inserted and removed freely.
Further, in the optical path of the objective lens system 102 (rear surface side of the objective lens system 102 in FIG. 8), a conversion lens 104 as a focus switching lens for changing the focal length of the objective lens system 102 is provided. The conversion lens 104 can be inserted and removed freely.
The polarization filter 103 is disposed in the optical path as needed and located at a proper polarization position by being rotated suitably.
Thus, a ghost reflection image, such as an image of the upper portion of an instrument panel or a dashboard within the vehicle interior, imaged on a front window can be prevented from entering into the objective lens system 102 and the CCD 101.
Further, a degree of the ghost imaged into the camera apparatus 100 can be reduced.